FIELD OF THE INVENTION
This invention relates to a bipolar electrosurgical instrument, and more particularly to a bipolar electrosurgical instrument having replaceable electrodes for sealing vessels and vascular tissue.
BACKGROUND OF THE DISCLOSURE
A hemostat is commonly used in surgical procedures to grasp, dissect and clamp tissue. It is typically a simple pliers-like tool that uses mechanical action between its jaws to constrict vessels without cutting them. It is also typical to have an interlocking ratchet between the handles so that the device can be clamped and locked in place.
Many hemostats are used in a typical open-surgical procedure. Once vascular tissue has been clumped with a hemostat, it is common for a surgeon to tie a suture around the tissue to close it off permanently prior to removing the hemostat. Several hemostats may be left in the surgical field until the surgeon has the opportunity to tie a suture around each section of clamped tissue.
Neurosurgeons have used bipolar instruments to coagulate vessels in the brain that are smaller than two millimeters in diameter. These bipolar instruments are typically tweezers-like devices with two arms that can be deflected toward each other to grasp tissue. However, it has been found that these instruments are not capable of sealing blood vessels with diameters larger than about two millimeters. There has been a long-felt need for an easy way to seal larger vessels and vascular tissue bundles without the need for sutures.
It is thought that the process of coagulating small vessels is fundamentally different than vessel sealing. Coagulation is defined as a process of dessicating tissue wherein the tissue cells are ruptured and dried. Vessel sealing is defined as the process of liquefying the collagen in the tissue so that it crosslinks and reforms into a fuse mass. Thus, coagulation of small vessels is sufficient to permanently close them. Larger vessels need to be sealed to assure permanent closure.
A number of bipolar electrosurgical forceps and clamps are known in the field. However, these instruments are not designed to apply the correct pressure to a blood vessel to achieve a lasting seal. All of these instrument also suffer from the drawback that they do not combine the simplicity and familiarity of a hemostat with a bipolar electrosurgical circuit.
An example of a bipolar electrosurgical power curve for vessel sealing is disclosed in a U.S. Patent application entitled, “Energy Delivery System for Vessel Sealing,” Ser. No. 08/530,495, filed Sep. 19, 1995, and is hereby incorporated by reference and made a part of ties disclosure.
A U.S. patent application entitled, “Vascular Tissue Sealing Pressure Control and Method,” Ser. No. 08/530,450, filed on Sep. 19, 1995, discloses another surgical tool for sealing vessels, and is hereby incorporated by reference and made a part of this disclosure.
U.S. Pat. No. 371,664 discloses a pair of electric forceps with positive and negative electric poles located on the jaws.
U.S. Pat. No. 728,883 discloses an electrothermic instrument in which electricity is used to heat one of the jaws of the instrument.
U.S. Pat. No. 1,586,645 discloses a bipolar instrument for coagulating tissue.
U.S. Pat. No. 2,002,594 discloses a bipolar laparoscopic instrument for treating tissue, whereby coagulation and cutting of tissue can be performed with the same instrument.
U.S. Pat. No. 2,176,479 discloses an instrument for finding and removing metal particles. The jaws of the instrument are designed to complete an electrical circuit when conductive material is placed therebetween. An insulated pivot and an insulated ratchet are used to prevent a short circuit.
U.S. Pat. No. 3,651,811 discloses a bipolar electrosurgical instrument for cutting and coagulating tissue.
U.S. Pat. No. 4,005,714 discloses bipolar coagulation forceps with jaws that open and close by way of an actuating sleeve.
U.S. Pat. Nos. 4,370,980 and 5,116,332 disclose an electrocautery hemostats wherein the hemostatic clamping function and the electrocautery function may be accomplished with a single instrument. Monopolar electrosurgical designs are shown and described.
U.S. Pat. No. 4,552,143 discloses a family of removable switch electrocautery instruments, including an electrocautery hemostat. Monopolar electrosurgical designs are shown and described.
U.S. Pat. No. 5,026,370 discloses an electrocautery forceps instrument having an enclosed electrical switching mechanism. Monopolar electrosurgical designs are shown and described.
U.S. Pat. No. 5,443,453 discloses coagulating forceps having a plurality of electrodes.
U.S. Pat. No. 5,484,436 discloses bipolar electrosurgical instruments for simultaneously cutting and coagulating tissue.
The article, “The Mechanism of Blood Vessel Closure by High Frequency Electrocoagulation” discloses experiments upon the blood vessels of dogs. The sentence starting on the last line of page 823 describes “an electrode forceps, each of the blades being insulated form the other and each connected to a terminal of the high frequency generator.”
The article, “Studies on coagulation and development of an automatic computerized bipolar coagulator” discloses on page 150 that, “It was not possible to coagulate safely arteries with a diameter larger than 2 to 2.5 mm.” On page 151, line 5, it is noted that “Veins can be coagulated safely up to a diameter of 3 to 4 mm.”
Russian Patent 401,367, translation enclosed, discloses a bipolar instrument with a linkage that brings the working jaws together in a parallel manner.
Prior disclosures have not provided a design for a bipolar electrosurgical instrument with removable electrodes capable of conveniently applying a constant pressure, from a calibrated spring-loaded source held by a ratchet, that is sufficient to seal vessels and vascular tissue.
SUMMARY OF THE INVENTION
It is the general object of this invention to provide a bipolar electrosurgical instrument for sealing vessels and vascular tissue. The instrument is designed to grasp and clamp vessels or vascular tissue between its jaws. The jaws have removable electrodes that are electrically connected to an electrosurgical generator. Electrosurgical current flows through the clamped tissue between the electrodes. The instrument is bipolar because electrosurgical current flows from one electrode, through the tissue, to another electrode, and both electrodes are located on the instrument. In contrast, a monopolar instrument requires a separate electrode (sometimes called an “neutral electrode”) that is located remote from the instrument.
One of the advantages of the instrument is that vessels and vascular tissue can be sealed without the use of sutures, staples, or other material that is foreign to the tissue.
Another advantage of the instrument is that the removable electrodes provide safety against electrical shocks and bums. Electrically insulative materials, such as plastics, can be damaged or compromised by repeated serialization cycles. It is also possible for electrical insulation to be cut or nicked by sharp surgical tools. Removable electrodes provide a safety advantage because they can be replaced prior to each procedure. The electrodes can also be replaced at any time if the surgeon suspects an electrical insulation failure. This advantage is particularly important for vessel sealing instruments because currents up to 4 amperes may be used.
The present invention is a bipolar electrosurgical instrument comprising first and second members having first and second jaws near a distal end, and having first and second handles near a proximal end. A pivot joint connects the first and second members to allow for arcuate motion of the first and second jaws toward each other. First and second mechanical interfaces are located respectively on the first and second jaws. The first and second mechanical interfaces are preferably shaped to removably mate with first and second electrodes. The mating portion of the electrodes are made from an insulative material to prevent electrical conduction to the members. Seal surfaces on the opposable electrodes are preferably designed to clamp vessels and vascular tissue and conduct electrosurgical current therethrough in a bipolar circuit. First and second interlocking ratchets are located on the proximal end of the members to provide a constant closure force between the seal surfaces.